Katy Perry says her pal Rihanna is "so wild".

The two singers are firm friends and have enjoyed nights out and holidays together.

It can be notoriously hard for people in the showbiz industry to form close bonds and Katy revealed why the 25-year-old Bajan star is the perfect best buddy.

"She is so down to earth, but also so wild!" she gushed to the UK edition of OK! magazine.

"We share a lot of stuff when we get together. I'm drawn to genuine personalities and people who aren't affected by this spotlight - Ria [Katy's nickname for Rihanna] is so unaffected."

Both stars have dealt with difficult breakups in the past, with Katy divorcing comedian Russell Brand in December 2011 and Rihanna's on/off relationship with Chris Brown coming to an end in May last year.

Initially it was reported their tumultuous love lives had driven a wedge between the girls, but they both insist they are as close as ever.

Katy also offered her thoughts on Miley Cyrus, who endured a public split with her fiancé Liam Hemsworth towards the end of last year.

"Miley's just a sweet girl and doesn't care what anyone thinks," she smiled.

"Other girls in this business aren't so friendly - they're secret mean girls. I like to hang out with the unaffected girls, like Rihanna."

Katy, 29, has previously admitted she contemplated suicide when her romance with Russell fell apart.

She now wishes she'd spoken out sooner and let her loved ones help her out.

"I went through a very sad and difficult spell," she revealed.

"I was struggling with very negative thoughts. I should have reached out to my friends instead of burying it all inside me. We shouldn't be ashamed of those terrible dark moments."